Some ethnic groups have higher levels of this hormone than others. While it can boost performance in competitive sport, there is a downside.
Ross, Ronald; Bernstein, Leslie; Judd, Howard; Hanisch, Rosemarie; Pike, Malcolm; Henderson, Brian (1986) Serum Testosterone Levels in Healthy Young Black and White Men, JNCI: Journal of the National Cancer Institute, Volume 76, Issue 1, January 1986, Pages 45–48
Bermon, Stephane; Garnier, Pierre-Yves (2017) Serum androgen levels and their relation to performance in track and field: mass spectrometry results from 2127 observations in male and female elite athletes, British Journal of Sports Medicine, Volume 51 Issue 17
Reich, David (2018) Who We Are and How We Got Here, Oxford: University of Oxford Press